Wire tuning drive



Oct. 14, 1952 D. B. KEIM 2,613,540

WIRE TUNING DRIVE Fild June 15, 1951 Ihventor: Donald BKeim -Deceasecl,Arthur C. Kneibler-Administr-a-tor-,

His Attorneg.

Patented Got. 14, 1952 WIRE TUNING 'DRIYE Donald B. Keim, deceased, lateof Syracuse, N. Y.,

by Arthur C.- Kneibler, administrator, Syracuse, N. Y., assignor toGeneral Electric Company, a corporation of New York Application June 15,1951, Serial No. 231,872

The invention relates to radio tuning drive mechanisms and moreparticularly to a wire tuning drive mechanism adapted for use withtelevision broadcast receivers.

In many applications it is not desirable to connect a tuning condensershaft directly to an actuating control knob. Thus, many' tuning drivemechanisms incorporate atuning condenser. with means to turn therotorsat a much slower speed than the control knob. This results in moreaccurate control and is generally accomplished by means of frictiondrive pulley arrangements in which a large drivenwheel may be secured toa tuning shaft and in-peripheral frictional contact with a small pulleyturned by a suitable control knob. Other tuning drive mechanisms employa drive cord wrapped around the condenser tuning shaft and drive shaftwhich is turned by a similar control knob. However; these latter corddrive mechanismshaye proved; unsatisfactory for high frequencyapplications and. 1 television receiver tuning arrangements wh eslippage between the driving anddriven membe and absenceof directpositive drive cause undesirable operation includingobjectionableidetuning. I

Presently manufactured television receivers generally incorporate;,asocalled head end section which houses amng other elements theoscillator fine-tuning condenser connected through a suitable drivemechanism to a control knob as well as variable trimmer condensersforeach channel. It hasbeen found desirable to mount the trimmercondensers so that they may be accessible for servicing-and aligningfrom the front panel of such a section through which the tuningcondenser drive-shaft alsoextends. The tuning and trimmer c ondensersaregenerally located near one-another; -It will be apparent then thatatuning drivemechanism should be constructed so as nohto obstruct, thetrimmer:

It is another obj ectof'I-the-invention to providea tuning drivearrangement which permits adjustment of internal control elements,located behind a television chassis panel, despite the proximity ofthese elements'to the-tuning drive mechanism.

6 Claims. (01. 74-10.s)

Another object of the invention is to provide a friction tuning drivemechanism for a television broadcast receiver in which thetuningcondenser shaft is driven by an incomplete wire ring-like memberunsupported over a large portion of its circumference which permitstuning and aligning tools to be inserted inside the wire ring to adjustother elements of the receiver.

It is a further object of the invention to provide a tuning drivemechanism having a wire ring-like drive member in which the insulatingsupport for the wire acts as an automatic stop member preventing damageto the mechanism when improperly operated.

For additional objects and advantages and for. a better understanding'ofthe invention, attention is now directed to the following descriptionand accompanying drawings. The features of the invention which arebelieved to be novel are particularly pointed out in the appendedclaims. In the drawings, Fig. 1 is a front elevation of the tuning drivemechanism and panel as might be viewed along the line :r--r' of Fig. 2,Fig. 2 is a side elevation, partly in section, of the tuning drivemechanism and panel, Fig. 3 is a front elevation of one modification ofthe wire ring-like drive member shown in Fig. l, and Fig. 4 isa sideelevational view, partially in section, taken along the line y-y' ofFig. 3.

As heretofore stated, the improved drive mechanism has particularapplication to a televisionbroadcast receiver. Therefore, in Fig. 1,there is shown a chassis panel member I of such a receiver. This panelhas a plurality of circularly arranged spaced-apart control apertures 2,through which certain system control elements may be reached foradjustment and servicing purposes.- In this particular case, theycomprise trimmer condenser screws3 located in circular arrangement andcorresponding in number to the number of channels received by thetelevision set.

In this embodiment, as in others referred to heretofore, the fine-tuningcondenser is located adjacent the trimmer condensers. There is shown-inthis figure a tuning condenser shaft 4 to which there is connected avariable condenser assembly 5 shown in outline form in Fig. 2. The shaft4 is suitably journaled in the panel member and is driven by means of aknob 5 (shown in Fig. 2) secured to a concentric sleeve or shaft member1 through a drive mechanism including a friction disc member 8 carriedby the sleeve 1 and 'a. wire ring-like drive member 9 connected theshaft 4. The wire ring-like drivemember r 3 9 comprises the incompletewire ring ill, the ends of which are secured within an insulatingmolded-plastic sectorial member I I. In order to fasten the ring Isecurely within the sectorial member I l, annular indentations l2 areprovided at the ends of the ring. The sectorial supporting memberll,which isof course thicker than the diameter of the wire, fits on thetuning shaft 4 and is held in placeby means of a flanged hub portion i3.This hub portion l3 includes keys M which fit into corresponding slotsin the tuning shaft and a fiat portion [5 fitting a correspond:-

ing fiat portion of the tuning shaft. The wire ring-like memberfrictionally' engages ;the disc member 8 whereby movement) ofzthe:control shaft l may be transmitted to the tuning shaft.

It will be seen that with this arrangement noneof the trimmer screws 3are hidden by the :wire

rotated within feasible limits without rendering the controls 3inaccessible.

It should be specifically pointed out that the tuning 'shaft'isinsulated from the ring by the sectorial member I 4, thereby minimizing"oscillatoi' radiation andstatic voltages which might be duetometalcontact between the metal frictiondisc 5 and the wire ring Ill orbetween the wire ring it and the tuning shaft 4. Also, in the embodimentgreater manufacturing assembly tolerances are permitted sincetheunsupported portion of the'ring It is slightly flexible allow ing formisalignment of'the ring I0 and the disc member8f There is shown in Fig.2a side view of the improved wire drive mechanism including a portion ofthe television cabinet l5, shown in outline, and the external controlknobs. The tuning controlknob 6 is fastened to the control shaf't'orsleeve 1 and an -se ne wire ring-like member 9 through "the' friction"disc member 8' secured thereto. The friction disc member 8 comprisesmetallic discs i and i8 whichare staked to the driving sleeve in itsannular slot IH'and spaced apart by anannular spacer which is thinnerthanthe diameter of the wire ring. It will be evident that with thisarrangement there is provided smooth metal to met'aldrive betweenthespring disc sheaths I1 and I8 andthe interfitting wire member l0, andfurther that the wire member ID is gripped between these discs at itsouter peripheral surfaces. There is "shown the two metallic discs asillustrating-a preferred embodiment of the invention "and it will beapparent that other friction drive means maybe employed, if desired, todrive the wire ring-like members.

' The tuning shaft or sleeve 1 is-concentric with another'shaft 2| towhich a selector knob 22 is attached. "This latter shaft functions tochange the necessary circuit connections within the chassis for thedifferent channel settings. For isolation purposes, this selector shaft21 is connectedto an insulating coupling 22a, which in' turn connects tothe channel selecting means 23 by a shaft ZSasupportedin a bearingmember-24.

As heretofore mentioned, the'position of the front cabinet [6 is'shownin outline. However, itwill' be appreciated that the receiver chassis,including the panel I and drive mechanism, are removed from the cabinetwhen the trimmer screws are to be adjusted. There is shown in thisfigure one means for adjusting these controls comprising the screwdriver25. It is to be especially noted that during the adjustment of certainof the trimmer controls that the screw- 4 driver extends through thewire ring-like member and the panel.

It will be evident from Figs. 1 and 2 that the driving mechanismprovides an inherent stop so that even though the front control knob 6is continuously rotated in one direction, there will be no damage to thefine tuning condenser 5 since the shoulder 26 on the plastic supportmember i l engages the disc drive members and prevents further rotationof the tuning shaft. The sectorial member ll occupies approximately 120within the total-area of the drive member 9 so that the tuning condensermay be rotated, in this particular application, as much as 240.

the control drive shaft or sleeve 1 are similar to th'ezhub portion l3of the sectorial member H in that they .both have key portions fittinginto corresponding slots 21 at the ends of their respective shafts.

In Figs. 3 and 4 there is shown a modification of the wire ring-likedrive member shown in Fig. l in which the insulating plastic sectorialmember 14 is replaced with a metallic member 28 having spring ears 29which grip the wire member it over duly a small portion of itscircumference. The member-28 is secured to the shaft by means of ahexagonal insulating cap or hub member 29. This cap or hubportion 29"fits on the-end of the shaft 4j'in'the sam'e manner as the hub 13 shownin Fig. l and'is secured to the metallic wire support member by means ofthe self locking clip 36." Referringto Fig. 4, which is a section alongthe line y-'-y "'of Fig; 3-, there is shown the hexagonal hub or cap 29secured to the clip 30 by means of the-oppositely disposed prong members3|. "Here-too, insulation is provided between the wire H! and the-tuning shaft by means of the insulating hub or cap' 29.

It'will thus'be apparent that there is provided tuning drive mechanismwhich is designed especially for use-in those television broadcastapplications in which it is desired to make receiver adjustments behindachassis panel adjacent to the fine tuning condenser and in which a wireringlike tuning shaft drive member is employed through which externaladjusting apparatus may be inserted to reach control elements behind thepanel. There is provided a tuning drive mechanism using an incompletewire loop which is unsupported over 'a large portion of itscircumference and driven 'by friction discs whereby suitable adjustingmeans may be inserted within the wire ring" as necessary for adjustingother elements of the system.

While a specific embodiment of the invention has been shownand describedand certain modifications therein have beensuggested, it will ofcourse-'-be undei-"stood that various other modifications maybe-madewithout departing from panel, two parallel shafts journaled to said'panel, means interconnecting said shafts for relative rotationwith-respect to each other comprisingadisc-"shaped member secured to oneshaft and a ring-like member secured to theother shaft, said ring-likemember comprising a relatively-resilient, arcuate, wire portion inperipheral engagement with said disc-shaped member and arelatively-rigid sectorial portion supporting the ends of said wireportion and means securing said sectorial portion to said other shaft,said wire portion being capable of slight radial deformation asnecessary to compensate for any slight misalignment between thecontacting surfaces of said two members.

2. A tuning drive mechanism comprising a panel, first and secondparallel shafts, means to journal said first shaft within said panel,means rotatably supporting said second shaft, means to connect saidshafts for relative rotation with respect to each other comprising adisc-shaped member secured to one shaft and a ring-like member securedto the other shaft, said discshaped member comprising a pair ofresilientlymounted, spaced, metal discs, said ring-like membercomprising a relatively-resilient, arcuate, w ire portion arranged to befrictionally gripped between said discs and a relatively-rigid sectorialportion supporting the ends of said wire portion and means securing saidsectorial portion to said other shaft, said wire portion being capableof slight radial deformation as necessary to compensate for any slightmisalignment between the contacting surfaces of said two members.

3. A tuning drive mechanism comprising a panel, first and secondparallel shafts, means to journal said first shaft within said panel,means to rotatably support said second shaft, means to connect saidshafts for relative rotation with respect to each other comprising adisc-shaped member secured to one shaft and a ring-like member securedto the other shaft, said ring-like member comprising an arcuate wireportion in peripheral engagement with said disc-shaped member and asectorial portion having means securing the ends of said arcuate wireportion thereto and including insulating means securing said sectorialportion to said other shaft.

4. A tuning drive mechanism comprising a panel having a plurality ofcontrol apertures, a tuning shaft journaled to said panel adjacent saidapertures, a control shaft rotatably mounted parallel to said tuningshaft, means interconnecting said shafts for relative rotation withrespect to each other comprising a disc-shaped 6 shaped member andhaving end portions secured within a sectorial support portion having aninsulating central hub portion fitting on the end member secured to saidcontrol shaft and a ring-like member secured to said tuning shaft, saidring-like member comprising an arcuate wire portion in peripheralcontact with said discof said tuning shaft.

5. A tuning drive mechanism for television receivers comprising a panelhaving a plurality of control apertures, a tuning shaft journaled tosaid panel adjacent said apertures, a control shaft rotatably mountedparallel to said tuning shaft, means interconnecting said shafts forrelative rotation with respect to each other comprising a disc-shapedmember secured to said control shaft in frictional engagement with aring-like member secured to said tuning shaft. said disc-shaped membercomprising a pair of metallic discs, said ring-like member comprising anarcuate wire portion in contact with said disc member between said pairof metallic discs and having and portions secured within an insulatingsectorial support portion having a central hub portion fitting on theend of said tuning shaft.

6. A tuning drive mechanism for television receivers comprising achassis panel, a tuning condenser drive shaft journaled to said panel, acontrol shaft mounted for rotation parallel to said tuning shaft, meansto rotate said control shaft, means interconnecting said tuning andcontrol shafts for relative rotation with respect to each other, saidmeans comprising a disc member secured to said control shaft and infrictional contact with a wire ring-like member secured to said tuningshaft, said wire ring-like member comprising an incomplete wire ringportion in contact with said disc member and supported by a sectorialinsulating portion having a central hub portion fitting on said tuningshaft whereby external adjusting apparatus may be inserted inside saidwire ring-like member and chassis panel.

ARTHUR C. KNEIBLER, Administrator of the Estate of Donald B. Keim,

Deceased.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,688,313 Pacent Oct. 16, 19281,928,310 De Jur Fowl? Sept. 26, 1933

